Scientists’ journey towards the goal of a nasal Covid vaccine does not stop. Many are studying it. And the topic is back topical with new research published in ‘mBio’, an open access journal of the American Society for Microbiology. In the new work, a team of US researchers shows the potential of a mucosal vaccine based on bacteriophages (or phages), i.e. viruses that exclusively infect bacteria and are used, making them express a piece of Sars-CoV-2, to induce a immune response in the nasal mucosa. The main gift? Scientists also speak of efficacy against contagion.
The ‘holy grail’ for those who study vaccines against Covid-19 is a shield that can also efficiently prevent viral transmission, as well as protect against serious disease. Mucosal immunity is believed to be the key to achieving this goal. In the new study, senior authors Venigalla B. Rao, of the Bacteriophage Medical Research Center at Catholic University of America in Washington Dc, and Ashok K. Chopra, of the Department of Microbiology and Immunology at the University of Texas Medical Branch in Galveston, jointly describe to colleagues the results obtained in mice with the intranasal administration of two doses – 21 days apart from each other – of a non-infectious mucosal vaccine based on T4 bacteriophages, multicomponent, without needle and without adjuvants.
In the experiments, the researchers observed that the vaccine induced robust immunity of the moss, as well as strong humoral and cellular systemic immune responses. The intranasal vaccine induced large neutralizing antibody titers against multiple variants of the virus and triggered a cytokine response, strong T cell immunity (CD4 + and CD8 +) and IgA antibodies (which characterize mucosal immunity) in high quantities in the sera and bronchoalveolar lavage of vaccinated mice. All of these responses were much stronger in the nasally vaccinated mice than those induced by the injected vaccine. In addition, the study authors continue, the nasal vaccine provided complete protection and sterilizing immunity against the mouse-adapted Sars-CoV-2 MA10 strain, the ancestral strain WA-1/2020, and the deadliest Delta variant in the models. murine. The T4-Covid-19 vaccine did not affect the gut microbiota, and is stable at room temperature, the researchers add.
“This vaccine administered intranasally – confirm Rao and Chopra – generates superior mucosal immunity in mice, as well as inducing robust humoral and cell-mediated immune responses and provides complete protection and sterilizing immunity against Sars-CoV variants. -2. The vaccine is stable, adjuvant-free and cost-effective produced and distributed, making it a strategically important next-generation Covid vaccine to end this pandemic. ” According to the two scientists, this platform, for a vaccine that does not require a needle, is also “an excellent candidate for designing effective mucosal vaccines against other respiratory infections and for preparing for any future emergencies” linked to epidemics or pandemics from emerging pathogens.
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